Modelling the depth profile of εNd in the ocean for the reconstruction of weathering patterns and siliciclastic input from the river basins.

Xu et al. (2018) explored the Nd isotope variability at two different depths viz., 500 m and 2800 m, in the western Philippine Sea. While the Nd isotopic signature did not exhibit any seasonal variability at 500 m depth, at 2800 m depth, it showed such a variation. Such an observation pointed out:

"rapid modification of εNd values during the settling of planktonic foraminifera by the precipitation of Mn coatings derived from water masses at deposition depths"

The εNd values are essential in deciphering the siliciclastic input, and a suitably designed work can lead to a better understanding of the variability of weathering in the river basins.

I suggest that the depth profile of εNd can be modelled akin to that of Total CO₂ by Goyet and Davis (1997). The results obtained from such a study might be very much useful to explore the water column properties of the paleo ocean and to reconstruct the siliciclastic input using the Nd isotopes extracted from well-preserved foraminifers.

For example, such research has potential applicability in the exploration of temporal variability in the weathering pattern and the exploration of siliciclastic input to the South China Sea from the island of Borneo. The Borneo has faced rapid upliftment, and intensive weathering is underway. Such a place is ideally suited for quantifying the variability of siliciclastic input to the adjacent South China Sea. Some other areas where this type of work can be carried out include the Southern Alps in New Zealand and the Himalaya mountains.

References:

Xu, Z., Li, T., Colin, C., Clift, P.D., Sun, R., Yu, Z., Wan, S., Lim, D., n.d. Seasonal variations in the siliciclastic fluxes to the western Philippine Sea and their impacts on seawater εNd values inferred from one year of in situ observations above Benham Rise. Journal of Geophysical Research: Oceans. https://doi.org/10.1029/2018JC014274

Goyet, C., Davis, D., 1997. Estimation of total C02 concentration throughout the water column. Deep Sea Research Part I: Oceanographic Research Papers 44, 859–877. https://doi.org/10.1016/S0967-0637(96)00111-2